Multiple gate field effect transistors (FETs) are metal-oxide-semiconductor field effect transistors (MOSFETs) that incorporate more than one gate into a single device.
One specific type of multiple gate FET is the finFET, which wraps the conducting channel with a thin fin forming the gate of the device. The effective channel length of the device in this case is determined by the thickness of the fin (measured from source to drain). The wrap-around structure of the gate provides improved electrical control over the channel, and thus helps to mitigate leakage current and other short-channel effects. However, as the fin width approaches five nanometers or greater, channel width variations in the finFET may cause variability and mobility loss
These effects can be mitigated by forming the FET as a gate-all-around (GAA) FET, which is similar to the finFET, except that the gate material surrounds the channel region on all sides. GAA FETs provide a static electrical field from all directions.